Rockwell Automation 2755 2D Hand-Held Scanner - Manual (Page 122)

G–8 Glossary
Publication 2755-6.4
L
Laser
An acronym for Light Amplification by Stimulated Emission of
Radiation. The laser is an intense light source. Light from a laser is
all the same frequency, unlike the output of an incandescent bulb.
Laser light is typically coherent and has a high energy density.
Laser Spot Size
The diameter of the spot of laser light scanning the bar code, as
measured at a given distance from the bar code. Smaller spot sizes
yield higher resolution but power depth of focus.
Laser Diode
A gallium-arsenide semiconductor type of laser connected to a power
source to generate a laser beam. This laser type is a compact source
of coherent light.
LED Indicator
A semiconductor diode (LED – Light Emitting Diode) used as an
indicator, often in digital displays.
M
Mil
1 mil = 1 thousandth of an inch.
Minimum Reflectance Difference (MRD)
The difference in percentage between light reflected from spaces
(Rs) and light reflected from bars (R
B
). MRD = %R
S
– %R
B
.
Misread
A condition which occurs when the data output of a reader or
interface controller does not agree with the data decoded within a bar
code symbol.